Stripper



FIPSSD? XR zsgft cfil'i tented July 7, 1936 UNITED STATES Search PATENT OFFICE STRIPPER- David Julian Block, Winnetka, 111.

No Drawing. Application July 27, 1934, Serial No. 737,313

8 Claims.

This invention relates to an improved stripper, and more particularly to the use of calcium monophosphate or its equivalent in connection with strippers of the reducing type.

The action of strippers upon dyes and pigments is well known, although the mechanism thereof is not completely understood. It has now been discovered that the addition of monocalcium phosphate to strippers of the socalled reducing type considerably improves the action thereof, so that considerably greater bleaching action may be obtained therefrom.

The monocalcium phosphate appartently acts as a catalyst, and the chemistry of the reaction is not understood. Other phosphates do not appear to give the same results, except in the case of ammonium phosphate, which has the same general effect, but to a lesser degree. The phosphate has proved effective on all reducing strippers tested, including particularly those containing sulfur. It has improved the action of such commercial strippers as Rit or Tintex, the latter being a zinc dust stripper.

The monocalcium phosphate has proved particularly effective in connection with a stripper comprising normal zinc su1foxylateformaldehyde, sodium hyposulfite (Na2S2O4) and sodium bisulfite. The phosphate will increase the stripping action of each of these ingredients individually, or in any combination, but it is preferred to use it in combination .with all three.

The preferred stripper comprises:

Parts Monocalcium phosphate Basic zinc sulfoXylate-formaldehyde 2 Sodium hyposulfite 2 Sodium bisulfite 1% Where this is to be used, as described in my copending application Ser. No. 737,314, filed July 27, 1934, in a combined oxidizing and reducing stripper, the monocalcium phosphate is increased, say to 2 parts, to offset the alkalinity of the oxidizing material, but other acids, such as formic acid, may be used to accomplish this result.

The above stripper, even without the monocalcium phosphate, has been found definitely superior to any other known reducing stripper, but its efliciency is very much increased by the addition of the monocalcium phosphate. Where the stripper is used without monocalcium phosphate, the proportions of the remaining ingredients are the same as stated in the above example.

It is of course understood that in place of 5 sodium salts here mentioned other alkali metal salts, including ammonium, may be used.

Magnesium hyposulfite may be substituted for the sodium hyposulfite, but it is not as efficient.

The term stripper as used herein applies 10 not only to the stripping of dyes, but to bleaching of dyed or undyed materials as well.

The foregoing description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claims should be construed as broadly as permissible, in view of the prior art.

What I claim as new and desire tosecure by Letters Patent is:

1. A reducing dye stripper comprising a dyestripper reducing agent and a compound of theclass consisting of monocalcium phosphate and ammonium phosphate.

2. A stripper as set forth in claim 1, in which 25 said compound is monocalcium phosphate.

3. A stripping compound comprising zinc sulfoxylate-formaldehyde, a hyposulfite, an alkali metal bisulfite, and a catalyst of the class consisting of monocalcium phosphate and ammo- 30 nium phosphate.

4. A dye stripper as set forth in claim 3, in which the catalyst is monocalcium phosphate.

5. A dye stripping compound comprising two parts zinc sulfoxylate-formaldehyde, two parts sodium hyposulfite (NaZSZOi) and 1 parts sodium bisulfite.

6. A dye stripper comprising approximately =34 part monocalcium phosphate, 2 parts zinc sulfoxylate-formaldehyde, 2 parts sodium hyposullite, and 1 parts sodium bisulfite.

'7. A dye stripper comprising zinc sulfoxylateformaldehyde, sodium hyposulfite, and sodium bisulfite.

8. A dye-stripper as set forth in claim 1, in 45 which the reducing agent is a dye-stripper of the sulfur type, and in which the phosphate compound is monocalcium phosphate.

DAVID JULIAN BLOCK. 50

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